As you rise to the occasion, your penis contains spongy erectile tissue that fills with blood, thus determining the size of your erection. Unfortunately, the tissue isn’t easily changed, according to Walsh. "These fibrous cylinders are fixed to the pelvic bone, and by virtue of being fixed to the pelvic bone, they are not easily manipulated,” he says. “They are fixed in place, and for most men, the length of the penis that they achieve through puberty becomes their maximum length.”

The vacuum pump. This is a cylinder that sucks out air. You stick your penis in and the resulting vacuum draws extra blood into it, making it erect and a little bigger. You then clamp off the penis with a tight ring -- like a tourniquet -- to keep the blood from leaking back into your body. What are the drawbacks? The effect only lasts as long as you have the ring on. Using it for more than 20 to 30 minutes can cause tissue damage. This is sometimes used as a treatment for erectile dysfunction, but has not been proven to actually increase the size of the penis.
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